Hypodermic syringe



March 19, 1929. A

F. J. HOFSCHNEIDER HYPODERMIC SYRINGE Filed Nov. 5, 1925 IIHII IIIIIHIIIHIIIIII f .about the stated results with a simple con- Patented Mar.Y19, 1929.

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FREDERIC J. Henson-Namen, or ROCHESTERy NEWYOBK.

HYPODERMIC svn-men Application led November My invention relates to ahypodermic syringe, and has for its principal object to aord a durable,efficient, and economical all metal construction, such that it can bethor,- oughly sterilized, and is adapted for dentists use.

A more particular purpose of the improvement is to afford an arrangementthat permits a needle carrier to be held in operative relationship tothe barrel of a syringe solely by. frictional engagement, thuseliminating the necessity of attaching means for the needle carrier.

An additional object of the invention is to construct and hold theneedle carrier in such manner as to afford a thoroughly water-tightconnection while making it possible to position or remove the needlecarrier instantly and without difiiculty. v

Still another purpose of the improvement is to attach a needle within aneedle carrier in such mannerv as to permit sufficient flexibility ofthe needle to prevent ready breakage, thus increasing the life of theneedle by causing it to withstand any ordinary stra-ins to which it maybe subjected.

A further object of the invention is to af-` ford a watertightconnection between thek piston and barrel of a syringe withoutemployment of washers of leather, soft metal, or the like, and toaccomplish this result with a part or partsV formed Vof hard metal and`constructed so as to be elastic. s l

An additional purpose of the invention is to afford an arrangement thatpermits 'of quickly and. effectively gripping thevpiston, to produce awater-tight connection between it and the barrel of the syringe, bymeans of an elastic, hardfmetal unit.

A Jfurther object of the invention is tobring struction and arrangementof parts that can be manufactured at a low cost, giving to the user astructure that will stand up successfully under hard, long` usage andwhich can be thoroughly sterilized Without taking apart. K

Vith these and other ends in view, the invention includes the form andarrangement of parts that will appear clearlyfrom the followingdescription when'read in conjunc` .tion withrthe accompanying drawings,the novel features being pointed out in the claims following thedescription.

In the drawings:

Figure l is a side elevation of a hypodermic 5, 1925. vserial No.`67,144.

syringe made in accordance .with one embodiy Figure l is a similar Viewshowing a slightly modified form of needle carrier ;l

Figure 5 1s an elevation of the lnner end of the needle carrier 5'Figure 6 is a detail sectional view of the sleeve used to tighten thegripping vmember about the piston, and

Figure 7 is a detail side elevation of the needle carrier, showing aportion of the syringe barrel in sectionand illustrating the pistonhandle in position when used to remove the needle carrier from thebarrel. l

The various features ofrmy invention may be carried out in manydifferentways, and the several arrangements herein shown are intendedmerely as exemplary of' various possible practical embodiments.

In vthe arrangement shown, l designates the barrelof a syringe,- 2 isthe piston, and 3 is the piston handle, which will be referredto Thebarrel l isy providedlwith a tapered openingfat its outer end to receiveVa needle more fully hereinafter.

carrier 4 whichhas an exterior surface tapered correspondingly with theopening in the barrel, and adapted to be held in the bar- ,rcl solely byfrictional engagement. The in- `ner end of the needle carrierihas areversely tapered portion 5 providedwith sediment K deflecting means,preferably in the form of a spiral groove which acts, as the piston isforcedinwardly, to cause any heavy particles in the fluid to be swirledto the side wall of the barrelv and retained in the pocket 7.

8 designatesv a needle, rigidly secured to the carrier at the rear endofthe latter, as designated at 9, either by soldering, compression ofthe carrier, or in any other suitable manner. Exceptrwhere the needle isattached at the rear end of the carrier, it is free from the adjacentwalls ofthe carrier. The latter is preferably provided with an enlargedopening at its centralportion having concave walls 10, and a reducedportion formed.

. end of the opening being flared as at 12.

This arrangement permits the needle to be flexed throughout its lengthas it'meets with,v

resistance and prevents it from breaking as v a fine gauge needle isused, the arrangement of Figure 4 is preferable. In this arrangement,the inwardly projecting portions 13 of the carrier are in contact withthe needle, although not connected thereto, and serve to brace theneedle at this point,while at the same time permitting endwise movementand flexing of the needle. The needle carrier may be provided with aseries of annular grooves 14 in its tap-ered surface which act to createa tighter and more perfect union with the surrounding tapered surface ofthe barrel, since the sharp edges afforded by the grooves have atendency to finish the surface of the barrel or remove any slightirregularities each time the needle carrier is forced into position. j

To assemble the needle carrier in the barrel, the piston 2 must first beremoved. The needle carrier is then dropped in the upper end of thebarrel and permitted to fall into the lower end. Then by inserting thepiston and slightly tapping the inner end of the needle carrier, thelatterV is properly positioned and is held frictionally until removed bya blow or suflicient pressure upon the outer end of the needle carrier.When desired to remove the needle carrier for steriliz'ing the parts,ifthe needle is worn out or broken, a blow upon the outer end of theneedle carrier will loosen 'and permit it to drop out of thebarrel,after the piston has been first removed. If it is desired to'preservethe needle and remove the needle and carrier from lthe barrel, theportion 15 of the handle 3 is employed. The piston being removed fromthe barrel, the opening 16 of portion 15 is positioned over the needleand against the outer end of the carrier as shown in Figure 7, and asufficient pressure on the needle carrier can vbe then exerted to loosenit from the barrel,

withoutr damaging the needle. I will now describe the parts which serveto form a water-tight connection between the piston and barrel. *j

The practice heretofore has been to employ Washersof soft metal,leather, asbestos,

or other compressible material to effect a. liquid-tight joint betweenthe barrel and piston. This has the disadvantages that'with leather orasbestos, sterilization is not practically feasible, and where softmetal is employed, it is quickly rendered useless by distortion, andfrequent movement of the piston causes particles of the metal to chipoff and get into the hypodermic solution. To overcome. these objections,I have devised a joint that utilizes only hard metal, which is elasticbut not of the needle carrier.

normal position and release the piston when pressure is removed. Theouter surface of the piston-gripping cylinder is tapered as shownl andprovided with a series of parallel annular grooves 22 aiiordingintermediate rings 23, and permitting sufficient elasticity in thecylindrical portion 21 so that it may be compressed about the piston 2without being permanently distorted. This action of the piston-grippingcylinder' may be brought about by a sleeve 24 having an inner taperedsurface 25 that engages ythe correspondingly tapered surface of thepiston-gripping. cylinder portion. The sleeve 24 is threaded interiorlyat its lower end to engage a threaded portion 26 on the barrel and byturning the sleeve 24 so as to thread it on the barrel, its taperedsurface forcing against the tapered surface on the piston grippingcylinder. coinpresses the latter around the piston 2. lVith very littleeffort, a sufficiently tight engagementbetween these parts can beobtained to prevent any loss of liquid between the piston and barrel. j

In order to turn the sleeve 24, it is provided with a keyway 2T that isengaged by a corresponding key 28 on the handle portion 3 of the piston,see Figure2. In this way, the sleeve 24 is tightened by a slight turningmovement of the handle 3 and piston with the latter in position in thebarrel, and may be loosened in the same manner.v 29 is a hammer portionon the handle that is used to knock the needle carrier from the barrelwhen the needle is broken or Worn out. Under these conditions, thekneedle carrier is removed by tapping its outer end" with the hammerportion 29.

In using the syringe, assuming it to be disassembled, a needle carrieris dropped into the upper end of the barrel 1 with the needle 8 pointingdownwardly, so that when it falls to the lower end of the barrel itassumes the position shown in Figure 2. The piston 2 is then insertedand pushed downwardly into the barrel to impose pressure on the innerend This forces the needle carrier into suiiiciently tight frictionalengagement with the barrel to retain it in place. The piston being inposition, the keyl 28 is then brougl'it into engagement with the keyway27 and piston handle 3 turned until sufficiently tight engagement is hadbetween the piston and piston-gripping cylinder to permit free movementof the piston and yet preprevent loss of liquid. The parts are thenready for operation and the piston may be removed to permit filling thebarrel with the necessary liquid. Thereupon the piston is 'againinserted and the device is ready for use upon a patient.

IVhile I have described the various features of my invention withreference to certain more or less particular embodiments, it is notrestricted inV its application to the details set forth, but may be usedin variousl Ways Without departing-from thev underlying features of theinvention or the scope of the following claims.

I claim: i

l. In a hypodreinic syringe, the combination With a bari'el having anopening which tapers toward its outer end, ot' a correspondingly taperedquickly removable needle carlriei` coperating With said tapered openingin the barrel and held therein solely by frictional engagement, thetaper of the barrel and carrier beingsuch that the liquid pressureWithin the syringe tends to tighten the carrier in the barrel.

2. In a hypodermic syringe, the lcombination with a barrel having atapered opening, Y of a needle carrier having a correspondingly taperedportion adapted toit in said opening and held there solely by rictionalengagement, said tapered portion of the needle carrier being providedWith a series'of'concenti-ic grooves.

3. In a hypoderinic syringe, the combina-k tionvvith a barrel having atapered opening, ot a needle carrier having a correspondingly taperedportion adapted to fit in said opening and held in the barrel solely byrictional engagement, the needle carrier having a reversely taperedportion at its inner end pro- 4vided With sediment detlectiiig means.

4. In a hypodermic syringe, the combinationWith a barrel having anopening'which tapers toward its outer end, of a correspondingly tapered,quickly removableneedle carV rier cooperating With said tapered openingin the barrel and held therein solely byfrictional engagement, theneedle carrier having an opening extending centrally, a needle arrangedin said opening'with its inner end FREDERIC J. HOFSCHNEIDER.

